FbTk::Lua - a class which augments lua::state with additional features

3 files changed, 183 insertions, 0 deletions

diff --git a/src/FbTk/LuaUtil.cc b/src/FbTk/LuaUtil.cc
new file mode 100644
index 0000000..456abac
--- /dev/null
+++ b/src/FbTk/LuaUtil.cc
@@ -0,0 +1,104 @@
+// LuaUtil: Various additional functions for working with lua
+// Copyright (C) 2011 Pavel Labath
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "LuaUtil.hh"
+
+namespace {
+    int newindexDenyWrite(lua::state *l) {
+        if(l->isstring(-2))
+            throw std::runtime_error("Cannot modify field '" + l->tostring(-2) + "'.");
+        else
+            throw std::runtime_error("Cannot modify this field.");
+    }
+
+    int newindexDenyModify(lua::state *l) {
+        bool ok = false;
+        l->getmetatable(-1); {
+            l->rawgetfield(-1, "__index"); {
+                l->pushvalue(-4); l->rawget(-2); {
+                    if(l->isnil(-1))
+                        ok = true;
+                } l->pop();
+            } l->pop();
+        } l->pop();
+
+        if(ok) {
+            l->pushvalue(-2);
+            l->pushvalue(-4);
+            l->rawset(-3);
+        } else 
+            newindexDenyWrite(l);
+
+        return 0;
+    }
+}
+
+namespace FbTk {
+
+Lua::InitFunctions Lua::s_init_functions;
+
+Lua::Lua() {
+    InitFunctions::const_iterator it_end = s_init_functions.end();
+    for(InitFunctions::const_iterator it = s_init_functions.begin(); it != it_end; ++it)
+        (**it)(*this);
+}
+
+void Lua::makeReadOnly(int index, bool only_existing_fields) {
+    checkstack(6);
+    lua::stack_sentry s(*this);
+    index = absindex(index);
+
+    newtable(); {
+        newtable(); {
+            pushnil(); while(next(index)) {
+                pushvalue(-2); pushvalue(-2); rawset(-5);
+
+                pop(); pushnil(); rawset(index);
+
+                pushnil();
+            }
+        } rawsetfield(-2, "__index");
+
+        pushfunction(only_existing_fields ? &newindexDenyModify : &newindexDenyWrite);
+        rawsetfield(-2, "__newindex");
+
+        pushboolean(false);
+        rawsetfield(-2, "__metatable");
+    } setmetatable(index);
+}
+
+void Lua::readOnlySet(int index) {
+    checkstack(2);
+    lua::stack_sentry s(*this, -2);
+
+    getmetatable(index); {
+        rawgetfield(-1, "__index"); insert(-4);
+    } pop();
+
+    rawset(-3);
+    pop();
+}
+
+} // namespace FbTk
diff --git a/src/FbTk/LuaUtil.hh b/src/FbTk/LuaUtil.hh
new file mode 100644
index 0000000..cdd1934
--- /dev/null
+++ b/src/FbTk/LuaUtil.hh
@@ -0,0 +1,78 @@
+// LuaUtil: Various additional functions for working with lua
+// Copyright (C) 2011 Pavel Labath
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+#ifndef FBTK_LUAUTIL_HH
+#define FBTK_LUAUTIL_HH
+
+#include <vector>
+
+#include "Luamm.hh"
+
+namespace FbTk {
+
+/*
+ * This class augments lua::state with additional functions/features. Every object automatically
+ * calls registered init functions, which can be used to initialize/create global variables in
+ * the lua state. Functions can be registered by calling registerInitFunction or by creating
+ * objects of type RegisterInitFunction.
+ */
+class Lua: public lua::state {
+public:
+    Lua();
+
+    /* 
+     * makeReadOnly() makes the table at the specified index "read only". This means that any
+     * attempt to modify a table entry will result in an error (if only_existing_fields is
+     * false). If only_existing_fields is true then only fields that were present at the time of
+     * the call will be protected - user can add new entries and modify them afterwards. You
+     * should avoid raw access to "read only" tables -- it might not do what you think it will.
+     */
+    void makeReadOnly(int index, bool only_existing_fields = false);
+
+    /* 
+     * readOnlySet() is the equivalent of settable, except that it works on "read only" tables.
+     * It can be used to modify protected entries or create new ones.
+     */
+    void readOnlySet(int index);
+
+    template<typename Functor>
+    static void registerInitFunction(const Functor &fn) {
+        s_init_functions.push_back(new SlotImpl<Functor, void, Lua &>(fn));
+    }
+
+    class RegisterInitFunction {
+    public:
+        template<typename Functor>
+        RegisterInitFunction(const Functor &fn) {
+            registerInitFunction(fn);
+        }
+    };
+
+private:
+    typedef Slot<void, Lua &> InitFunction;
+    typedef std::vector<InitFunction *> InitFunctions;
+
+    static InitFunctions s_init_functions;
+};
+
+} // namespace FbTk
+
+#endif // FBTK_LUAUTIL_HH
diff --git a/src/FbTk/Makefile.am b/src/FbTk/Makefile.am
index fc80dd4..011ba38 100644
--- a/src/FbTk/Makefile.am
+++ b/src/FbTk/Makefile.am
@@ -71,6 +71,7 @@ libFbTk_a_SOURCES = App.hh App.cc \
         Util.hh \
         RelCalcHelper.hh RelCalcHelper.cc \
         Luamm.cc Luamm.hh LResource.cc LResource.hh LResourceHelper-lua.cc \
+        LuaUtil.cc LuaUtil.hh \
         ${xpm_SOURCE} \
         ${xft_SOURCE} \
         ${xmb_SOURCE} \